Evaluation of different conditions to enhance the performances of Lactobacillus pentosus OM13 during industrial production of Spanish-style table olives

The main objective was to set up a methodology to improve the high volume production of green table olives, cv. Nocellara del Belice. Lactobaccillus pentosus OM13 was applied during three different industrial processes of table olives as follows: trial one (IOP1) was subjected to an addition of lactic acid until a brine level of pH 7.0 was reached; trial two (IOP2) subjected to same addition of lactic acid as in trial one plus nutrient adjuvant; and trial three (IOP3) subjected to same addition of lactic acid as in trial one, but with the strain L. pentosus OM13 acclimatized in brine for 12 h before inoculation. These trials were compared against two untreated controls (spontaneously fermented and addition of L. pentosus OM13 only). Within the third day of fermentation, the pH of the brines decreased significantly, reaching pH 4.85 for trial three, pH 5.15 for trial two, and pH 5.92 for trial one. The pH of both controls decreased more slowly, and had values below pH 5.0 only after the fifteenth day of fermentation (control one) and the sixty-fifth day of fermtation (control two). Trial three reached the highest lactic acid bacteria (LAB) concentration on the third day of fermentation. After six days of fermentation, all trials showed similar values of LAB counts that were significantly higher compared to control number one. The result from genotypic identification showed that L. pentosus OM13 was the most frequently isolated in the inoculated trials. Lactobacillus plantarum, Lactobacillus coryniformis and Pediococcus pentosaceous were also detected at very low concentrations. Homoguaiacol, 2-butanol, 4-ethylphenol, phenylethyl alcohol and 4-ethylphenol were the volatile organic compounds detected at the highest levels in all experimental trials. Trial three showed a higher concentration of squalene that was not detected in other trials. The highest sensory scores of green olive aroma and overall satisfaction were found for all experimental olives, especially for those of trial one and trial two, that differed significantly from the untreated controls. This study provides evidence that the addition of lactic acid, nutrient adjuvants and, most importantly, the acclimatization of LAB cells significantly shortens the acidification process of olive brine, and improves safety and sensory quality. Shorter acidification processes result in a more rapid transformation of table olives, with reduced commodity loss and lower costs of production compared to conventional manufacturing protocols

Effect of the mechanical harvest of drupes on the quality characteristics of green fermented table olives

Background: Because of damage caused by mechanical harvesting, the drupes for table olive production are traditionally hand harvested. Until now, no data have been available on the microbiological and chemical features of mechanically harvested drupes during fermentation. Results: Drupes mechanically harvested and inoculated with Lactobacillus pentosus OM13 were characterized by the lowest concentrations of potential spoilage microorganisms. On the other hand, drupes mechanically harvested and subjected to spontaneous fermentation showed the highest concentration of Enterobacteriaceae and pseudomonads during transformation. The lowest decrease of pH (4.20) was registered for the trials inoculated with the starter culture. Differences in terms of volatile organic compounds were estimated among trials. Multivariate analysis showed that the olives processed from the drupes mechanically harvested and inoculated with starter were closely related to control production (drupes manually harvested) in terms of microbiological and pH values. Sensory analysis evidenced negative evaluations only for the uninoculated trials. Conclusion: Drupes mechanically harvested and subjected to a driven fermentation with Lactobacillus pentosus OM13 determined the production of table olives with appreciable organoleptic features. Thus mechanical harvesting performed using a trunk shaker equipped with an inverse umbrella and the addition of starter lactic acid bacteria represents a valuable alternative to manual harvesting for table olive production at the industrial level